Ship hull



Get. 31, 1944. I I MUNRO 2,361,409

I SHIP HULL Filed Dec. 2, 1943 INVENTUR ATTORNEY Patented Oct. 31, 1944 UNITED STATES ATENT OFFICE sine HULL Gordon Munro, Dorchester, Mass. Application December 2, 1943, Serial No. 512,565

6 Claims.

This invention relates to ship construction and more particularlyto hull design. d

The main object of the invention is to provide a boat or ship hull of high efficiency and strength but of simple form and therefore of low cost.

As a general rule, in marinedesign, complication in hull construction has been justified to some degree by improved performance secured by the thus constructed hull. But construction costs increase so rapidly with complication in design that performance has almost always been sacrificed to some extent when cost was an essential factor, as is usually the case.

My invention provides a hull form which ,gives highly efficient performance but in which complications in building construction are minimized, and costs thereby reduced.

To this end, my hull is a combination hull and is based upon the utilization of a substantially flat-bottomed hull, Qrvariant thereof, supplemented by a complementary construction in the form of an added lower hull designed to overcome the performance deficiencies of simple fiat-bottomed hulls, particularly forward, where entrance characteristics are of predominating importance. In my construction, such desirable entrance characteristics are produced withoutsacrificing under-water performance of the submerged portion of the hull. In fact my construction permits the application of independent surface and submerged, design techniques aft of the entrance portion as will be hereinafter explained.

Secondly, my lower hull is of substantial crosssectional depth and stiffness, and extends fore and aft for such distance that it provides suflicient strength to prevent sagging and hogging. Costly details of keelson or deadwood construction are thus obviated.

Features of my hull may be more readily understood by reference to the accompanying draw.- ing illustrating a preferred example of my invention, in which:

Fig. 1 is aside elevation of a hull embodying my invention; I

Fig. 2 is a bottom plan view thereof;

Fig, 3 is an enlarged cross-sectional view indicating the exterior contour of the hull along th line 3-3 of Fig. 1;

Fig. 4 isa similar enlarged cross-sectional view indicating the contour of the hull along the line 44 of Fig. 1, and

Fig. 5 is a still further enlarged cross-sectional View taken along the lin 5-5 of Fig. 1, and illustrates certain construction details. l

As shown by the drawing, my hull is a combination hull formed of two component parts, an upper hull I and a lower hull 2. The upper hull I has a substantially flat bottom 6 and is suitably shaped longitudinally, as shown in Figs. 1 and 2, to distribute the displacement of water as desired. A preferred form of curvature of the sides I is illustrated in the drawing although this curvature may be increased or, decreased as desired or, for the purposes of simplicity and economy, the curvature may be eliminated to form a substantially straight line contour from the chine to the sheer or deck line. The deck 8 of upper hull l is shown as camberedythough in some constructions it may be flat in cross-section.

Unsatisfactory performance of the fiat-bottomed upper hull l is overcome by combining with the upper hull a simply constructed lower hull 2. The hull 2 extends from the stem aft a distance preferably substantially equivalent to the waterline length of the'combination hull and, in any event, .to some pointabaft midships and abaft the maximum beam of the'upper hull. The lower hull 2 is of such form that it may be combined with the substantially fiat bottom of the upper hull along a line of juncture H which may be and preferably is substantially a straight line athwart the ship throughout the length of the juncture. The forward end of such juncture is adjacent the forward end of the load water-line (indicated by dots and dashes) and may be above it (as shown in Fig. 1), or at or below the same.

As illustrated in Fig.2, the maximum beam of the lower hull 2. is at a point forward of the maximum beam of the upper hull l, and tapers forward of this point to a stem line forming. a continuation of the upper hull stem line It from a point just above the water-line. The lower hull 2 is so shaped that its upper side edges merge with, and become coincident with a. substantial length of, the upper hull chine lines. In the form shown in the drawing, the upper hull is flared forward and the forward side portions of the lower hull continue in fair curves the flare of the upper hull. In this particular case, highly desirable entrance characteristics are secured.

In order, howevento prevent the lower hull 2, aft of the forward portion, from detracting from performance of the combination hull, its maximum beam, as has been, previously stated, is carried forward of the point of maximum beam of the upper hull, and it is streamlined aft in order to offer the least possible resistance to its passage through the water. terior cross-sectional contour of the lower hull forward is substantially trapezoidal, as indicated Furthermore, while the exwelded to the bottom steel plating .6.

by Figs. 3 and 4, for the major'portion of its length aft its side portions become substantially vertical, as indicated at IS in Fig. 5, providing substantially rectangular cross-sectional contours. This box-like straight-sided, flat bottomed construction is th simplest type of construction whether the lower hull be made of metal or wood.

As will be readily seen, the sidings of the two hulls are designed independently of each other aft of the entrance area and consequently the upper hull may be designed for pleasing appearance and best surface performance while the lower hull may be independently designed for best submerged performance.

By utilizing the water-exposed under-portions 6 of the upper, hull .the water.

The partsl and may be attached togetherin accordance with established engineering princi- -ples and according to the particular materials .of which the two hulls are made. as shown in Fig. 5, the upper hull l, deck plank For instance,

ing. 8, deck beams 16, frames l1, and side planking '1 are'formed of wood, while'bottom :frames l9, bottom plating 6, chine angles.2l,'and gussets I8 are formed of steel .to provide a composite construction.

' The lower hull 2 is likewise formed of steel having welded-reinforcing plates 22, and may be In the case of such construction, bulkheads l2, l3, and I4,

aft into a skeg 20, it will be understood that other forms of sections aft of midships or aft of the point of maximum beam of the upper hull may be substituted. The lower hull, because of its substantial depth and because of its position extending atleast the major portion of the waterline length of the-combination hull, imparts a longitudinal rigidity sufiicient to withstand stresses whether afloat or ashore and permits elimination of any reinforcement in the form of deadwood along the median line of the upper hull.

As a result, the bottom frame angle irons :ldmay be uninterrupted centrally. This eliminates complications of fitting and labor usually encountered inkeelson or deadwood construction.

As will be readily understood, the invention can be incorporated in boats and ships of widely difierent size and type and of various forms of construction, including hydro-airplanes and pontoons. r

I claim:

1. A ship hull-having, in combinatioman upper hull, and a lower hullextending-fore and aft a distance equivalent to a major portion of the Water-line lengthof the ship, the cross-sectional juncture between saidhulls athwart saidship being substantially astraight line throughout the length of said juncture, said lower hull tapering aft and forward of its maximum beamgwith upper edges of the forward side portions-of 'th'e lower hull generally 'following the chine lines of said upper hull, and with said lower hull forward side portions conforming in general with forward side portions of the upper hull, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

2. A ship hull having, in combination, an upper hull, and a lower hull extending fore and aft a distance substantially equivalent to the waterline length of the ship, the cross-sectional juncture between said hulls athwart said ship being substantially a straight line throughout the length of said juncture, said lower hull having its :maximum beam forward of the maximum beam .forming'in, general with forward side portions of the upper hull, thereby providing desirable entrance characteristics for the combinationrhull,

and said lower hullside portions being carried aft-of said fairing portion independently of said upper hull side portions, thereby permitting in- .dependent lower hull submerged andupper hull surface design aftiof said forward fairingportion.

3. A ship hull having,.in-combination, an upper .hull, and a lower hull extending above the water- "line of the combination hull forward and extending aft to a point abaft midships, the crosssectional juncture'between said hulls athwart said fship being substantially a straight lineithroughout the length of said juncture, said lower hull tapering aft and forward of its maximum beam, with upper edgesofzthe forward side portions of -.the lower hull generally following the chine lines of said upper hull, and'with said lower hull forward side portions conforming in'general with for- .ward side portions 'of the. upper hull,'thereby pro- .vidingdesirable entrance characteristics for the combination hull, and said lower'hull side portions'being carried aft of said fairing portion independently of said upper hull side portions,

thereby permitting independent lower hull submerged and upper hull surface 'designaft ofsaid forward fairing portion.

'4. A ship hull having, in combination, a-substantially flat-bottomed upper hull havingside portions tapering to a stem line, and a lower hull substantially flat-bottomed throughout a. major portion of its length extendi'ng fore and aft a distance substantially equivalent to'the water-line length of theship,said-lower hull having an exterior contour substantially rectangular in cross-section athwart the-ship from its point of maximum beam aft and substantiallytrapezoidal in cross-section athwart the ship from said point forward, with upper edges of the forward side portions of the lower hull merging and becoming coincident with the chine lines of said upper hull, and with said lower hull forward side portions fairing together with forward=sideportions of theupper hull and tapering to a'line forming a continuation of said upper hull stem line, thereby providing desirable entrance characteristics for'the combination'hull, and said lower hull side portions being carried aftof saidfairing portion independently ofsaid upper hull side portions, thereby permitting independent lower *hull submajor portion of its length, said lower hull havn ing its maximum beam forward of the maximum beam of said upper hull and having an exterior contour substantially rectangular in cross-section athwart the ship from its point of maximum beam aft and substantially trapezoidal in crosssection athwart the ship from said point forward,

with upper edges of the forward side portions of the lower hull merging and becoming coincident with substantial lengths of the chine lines of said upper hull, and with said lower hull forward side portions fairing together with forward sideportions of the upper hull and tapering to a line forming a continuation of said upper hull stem line, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions. thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

6. A ship hull having, in combination, an upper hull having metal bottom plating, and a lower metal hull extending fore and aft a major portion of the water-line length of the ship and welded to the upper hull, the cross-sectional juncture between said hulls athwart said ship being substantially a straight line throughout the length of said juncture, said lower hull having its maximum beam forward of the maximum beam of said upper hull and tapering aft and forward of its maximum beam, with upper edges of the forward side portions of the lower hull merging and becoming coincident with the chine lines of said upper hull, and with said lower hull forward side portions fairing together with forward side portions of the upper hull, thereby providing desirable entrance characteristics for the combination hull, and said lower hull side portions being carried aft of said fairing portion independently of said upper hull side portions, thereby permitting independent lower hull submerged and upper hull surface design aft of said forward fairing portion.

GORDON MUNRO. 

